The decision of the Port of San Diego and the cities of Imperial Beach and Chula Vista to sue the U.S. branch of the binational International Boundary and Water Commission for allegedly violating the federal Clean Water Act is a proportionate, necessary response to a grave problem that only seems to get worse, not better. The port and the cities say they can no longer tolerate the commission’s failure to prevent sewage, trash, industrial waste and pesticides from flowing through the Tijuana River and into the Pacific Ocean on the U.S. side of the border. The pollution was severe enough that it led to the reported closure of parts of the shoreline in Imperial Beach for at least 160 days in 2015, 2016 and 2017.

The obvious initial response to this problem is for the U.S. and Mexican governments to commit to funding infrastructure improvements to sharply upgrade Tijuana sewage treatment facilities. This at the least would seem to require the involvement of Secretary of State Rex Tillerson and top aides to Mexican President Enrique Peña Nieto. But the response this week from the U.S. Justice Department shows why the lawsuit was necessary. It cites the need for any budget request to go to the State Department, then to budget officials and ultimately to Congress, where it would “of course [face] many competing demands” for federal funding.

In other words, addressing a pollution crisis with severe fallout at the U.S.-Mexican border is no more of a priority for the federal government than deciding whether to use federal funds to add a freeway off-ramp or to abate highway construction noise. It’s not enough for local agencies to say this is unacceptable. They deserve the strong backing of our regional congressional delegation and of California Sens. Dianne Feinstein and Kamala Harris.